This invention relates to solenoid controlled, pilot operated inlet water valves and more specifically to water valves used in household appliances such as dishwashers and clothes washing machines. This invention is an improvement on U.S. Pat. No. 5,082,240 issued to Richmond and which is hereby incorporation by reference.
One of the major sources of noise in appliance water valves can be cavitation which is the collapse of low-pressure bubble that occurs when water flows from a higher pressure, such as an inlet, to an area of lower pressure, such as a valving cavity of outlet. Low-pressure bubble collapse releases energy the causes structural vibration that can produce noise and erosion, fatigue and pitting in valve components. The problem of low-pressure bubble release is increased when hot water is used in a valve. Hot water is less stable and therefore creates more low-pressure bubbles under the same conditions than cold water. One way to reduce cavitation noise is to reduce water velocity prior to the water entering the lower pressure area.
Referring to FIGS. 1a-b, previous appliance water valves 20P have reduced cavitation noise by placing a solid surface 64P for water to strike soon after water passes through a flow control inlet 26P to initiate an early pressure recovery. Since the time for low-pressure bubble formation is decreased by water striking the solid surface 64P, fewer low-pressure bubbles are formed. A disadvantage of reducing cavitation noise by placing a solid surface 64P near the flow control inlet 26P is that the water flow rate may be reduced. An example of a providing a solid surface 64P for water to strike shortly after passing through a flow control inlet 64P is shown with the "noise suppression bullet" in U.S. Pat. No. 5,082,240 issued to Richmond.
Previous appliance water valves have also reduced cavitation noise by creating laminar flow scheme with baffles which cause water flow to change direction causing viscous friction to reduce water velocity. Examples of the use of a baffle to reduce water velocity can be found in U.S. Pat. Nos. 5,082,240 and 4,248,270 issued to Richmond and Ostrowski respectively.
For the foregoing reasons, there is a need to further reduce cavitation noise in appliance water valves without hindering water flow.